In the prior art of automatically and semi-automatically controlled vehicles apparatus has been provided to determine whether or not the vehicles performance has exceeded some commanded criteria. For instance, it is quite common, in vehicle control systems, to employ a vehicle speed governor which prevents the vehicle from reaching speeds above a particular speed limit. In particular, in the field of automatically controlled railroad vehicles a frequency responsive governor is illustrated in the prior art. This governor has applied to it control signals which are communicated to the vehicle, to define the vehicle's speed limit. In addition, the frequency responsive governor also receives a signal from a vehicle mounted tachometer or the like which signal has a frequency proportional to vehicle speed. The frequency responsive governor then is capable of determining whether or not the vehicle is exceeding a commanded speed limit. A typical example of such a frequency responsive governor is found in Butler et al U.S. Pat. No. 3,886,420.
Of course, vehicle speed limits are an important consideration in preserving the safe operation of the vehicle and the passengers and/or cargo carried by a vehicle. However, vehicle speed is also indicative of efficient operation of the transportation system of which the vehicle is but a part. Thus, for instance, if the vehicle is significantly under speed, that is, it is proceeding at a speed substantially below the speed limit, then while the system may be operating safely, it is certainly not operating efficiently. More important is the fact that if it were possible, in a fail-safe manner, to determine that the vehicle was proceeding within reasonable tolerance of commanded speed, it would be possible to accurately, and safely, predict vehicle position. With present day apparatus this is not possible since so long as the vehicle is in motion and below maximum speed limit it is considered operating properly. Obviously, under these conditions prediction of vehicle position is not possible with any reasonable degree of precision.
The foregoing is but one example of the need in the automatic transportation field for a vital universal performance monitor. The ultimate use of this would be to monitor vehicle performance and guarantee that the performance is within safe and efficient limits, i.e., both upper and lower limits.
It is therefore one object of the present invention to provide a vehicle performance monitor for determining, in a vital fashion, whether or not a vehicle is performing within acceptable bounds. It is another object of the present invention to provide such a vehicle performance monitor which is responsive to the same control signals which control vehicle speed. It is still another object of the present invention to provide a vehicle performance monitor as aforementioned which produces a signal indicative of expected vehicle performance which signal can be compared with a signal indicative of actual vehicle performance to determine whether or not the vehicle is performing properly in light of the received controlled signals.